In recent years, a portable terminal device provided with a touch panel, such as a smartphone or a tablet-type personal computer, is widely prevalent. In order to prevent any third party from illicitly manipulating the portable terminal device, the portable terminal device uses a password authentication in general. In a password authentication, the security strength is enhanced by increasing the length of the character string that is input and by making the character string more complicated. However, when the password is long and complicated, it is necessary for the user to type the keys many times when the user inputs the password, which is reduces the usability for the user himself/herself.
With regard to this issue, Patent Literature 1 indicates that, in order to maintain the balance between the user's usability and the security strength, location information about the portable terminal is obtained with a GPS (Global Positioning System) function provided with the portable terminal device, and the user is authenticated by using a short password when the user is at a location where the user is more likely to be located (e.g., home or workplace), and the user is authenticated by using a long password when the user is at a location where the user is less likely to be located (e.g., places visited in business trip or travel).
Patent Literature 2 indicates that, in order to appropriately arrange, on a terminal screen, an icon of an application corresponding to the location of a terminal, an icon of an application related to a current location is displayed on an upper half portion of the screen, and the icons of the other usual applications are displayed on a lower half portion of the screen.